I make the following mustard sauce with Christmas.

Mustard sauce:
• The yolk of 3 egg
• 1 tablespoon vinegar
• 3 teaspoon mustard with seeds
• 4 tablespoons sugar
• ½ cup stock (beef or chicken)

Instructions
In a mixing bowl, combine the egg yolks, vinegar, mustard, and sugar. Beat with a hand mixer. Transfer to a small saucepan and pour in the stock. Whisk and bring to a simmer. Remove from the heat and allow it to cool down.

It is delicious with cold meat. (•ิ‿•ิ)